Liquid level control



l 1 .1953 R. w. HIPPEN EI'AL 2,653,623

LIQUID LEVEL CONTROL Filed Jan. 23, 1950 2 Sheets-Sheet l I INVENT g 6 WW -www ATTORNEYS Sept. 29, 1953 W HIPPEN ETAL LIQUID LEVEL CONTROLFil-ed Jan. 23, 1950 2 Sheets-Sheet 2 lllllllll g Wm INVENTORS cea zm aZ. MonrrM.

the l iqgig level in Patented Sept. 29, 1953 4 I U T S TES 2,653,653LJIQUIP: LEVEL CONTROL elu aw fl m umllow. m extoh Lse Mu1 i hy, Sr.,Houston, Tex.

Ap pl iegtign J qn ng gfzb, 1950, Serial No. 140,188. 1 6" Glaixns. (C1,

g hi v o e s t h control iq he? t mid, Q-XE in o fis levels end morepartieolarlyto ine'jnsalotudtd tween gnggligvgeg by an element; that isinfllienced by variations the Leyel a of; the 1eve1= of the l-iquigjn a;tank orother vessel lgyel to f all Iiggti]; its formointaini-ngsaidflpvel between preQeter-mi-iaed Vic -vers,a. uppe! n wmi v QP QQQ a WW1 @Q 'Q QQ Various types of; liquid level control meanstype ohaxacte z:ip;e d i I I -Wh ikQh hugy; have-been devisedheretofore, utilizing either an nt rg ises m with the lievfei 0;actualfloat which rises and: ialls with the liquid whipfi'ea be level,or anelement having. an efiective specific gravity greaterv than that ofthealiquid and open- Q U 53 1 3%??? 193 3 t- 919 WWQWQ alting by. virtueof the difierence. in its.- efiective M H Weight when partially onentirely submerged; of; the, tyne Actuetingr elements of both types,which ar des: aot ated by vgififiw ii ated genericalm hereinafter as.buoyant el sahunm nd ,6 111111. .u m nts; hav e n. usedsto oprlatetvalves nother de ilxw ign, 'thgdiqfigg'lhteti .5 L t r; ontrol inth amount Qii isl e n'the mos is to vi e :1 imp ve? v sel. Em; examnloin e. as Qt: losed: Yc (ige qt he W Y. 2.1% e ezeeci ee hi e 5 3 3?SQQIA as suxggge tongs and 111111151 seogga; tively small buoyantelement can be used. tome; toas. e-. ott xock t ememkws sm we qme musgtg n g te heqqo xqngh fix q eotl'y een use; q eioeqt qo 2 Q" WW5 qr-fix; HQQ 1M; 1. fl fifil oviqg. I :Qxed mittin thgforc' W k ml-frirode'tin ou si e t e @5 1; o qo ssts who who ipwo en EQQIEX s s awqfin diston tbefl x b Q mes; cups A h t Qmxan mall amount 2 v messy mmai toembodiments; oi the momma 135K? 3% Qmxete thev alve and emote adfi smsms lus rr fieqsq aewzh t di ra t any in s worse o e h u h e let e vq sqm xqd- Me' bj ii it"? l fii' sly This. disad ant e i gswam het it ousfl r iq q vhofis sw at i r purbbse the available force is a functionoi the size of 3p mus ation onty' an -aire nth-"to be eonstiu'eda'so thebuoyant element whieh usually must he kept defi-mt'ion of-the most; theinvention, l eferen'o smelt ton prootical reasons; Further-mote, thebeing had to the abpended claims for'thispar-J motion in the flextube ortorque tube is conpose. tinuous as the liquid rises and falls around theIn said drawings) buoyant element, so that a small okwnngein the 35 Fig.'1 is a, diagrammatic layout showing the liquid: knob is sufllzcientto.actuate the pilot valve installation ainct operation of liquid: leveloontzrol' o her controll n mech nism and; Q ite qi n. m a m o yin h 'nvnt orii 23, thgqttlgng motion the g glye gos Its, Fig. 21's a, sectionalview. illustrating details oi Q39 Q53 the QP 'EQQS: i; 9% RQ$ 2 the p t-system; i s to gr oyide on impa oyeg 115;, evel qontgol q 49 Eig. 3:illustrates a seoond embodiment at the is whe i vir uall all; o the es-sd; invention: by the buoyant element is transmitted to 53 1}; sand;@fllnstrate different operating poo ailobie ol; the; uotat o of h vaveor ther sitionsofitheappamtusshown in. am

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A iux hqr q iect t w sle e m meq so: es t m na- WW; 2 e 9!, ql seo iesthe y e r IEFX-i v s "the a; Quid iss sk' hence the liquid level can beadjusted by any suitable means, here shown as a pipe 4 and a valveindicated diagrammatically at 5 and constituting either liquid inletmeans or, as in the example to be described below, liquid outlet means.If desired, the valve 5 can be operated by a suitable pilot valveindicated diagrammatically at 6, which may be simply a two-way cock or aslide valve controlling fluid pressure which actuates the main valve 5,or a more complicated pilot valve system of the gas-bleed-ofi type suchas used in present control practice. It will be understood, however,that the above details are not part of the invention, which can be usedwith various other types of apparatus and for any desired purpose.

The pilot valve 6 is operated by a buoyant element 1 of any suitabletype which is suspended inside the vessel in position to be partially orentirely submerged as the liquid rises from the level 3 to the level 2.As stated above, the buoyant element may be a float having lesseffective specific gravity than the liquid and rising and falling withthe liquid level. For most purposes and as shown, however, it ispreferable to use a buoyant element having greater effective specificgravity than the liquid and operating as a differential buoyancy mass,such as a leak-proof hollow vessel or a solid mass, such elements havingthe advantages of greater ruggedness and resistance to physical injury,as compared with floats. In the form shown, the buoyant element issuspended in a vertical tubular casing 8 for a purpose to be described,and for ease of installation and removal in such cases, the element maycomprise a suitable number of sections, the sections 9 and I beingjoined together and to the section 1 in any suitable manner.

The motion of the buoyant element is transmitted to the outside of thevessel substantially without dissipation by means of a link or rod thatis moved longitudinally by the buoyant element. Any suitable means canbe employed for translating vertical movement of the buoyant elementinto longitudinal movement of the rod or link.

In the form shown, the buoyant element is suspended from a horizontalarm H of a bell crank lever supported in any suitable manner and hereshown as pivoted at |2 on the tubular casing 8, preferably on aknife-edge which is hooded by the lever resting thereon so as tominimize the accumulation of foreign matter at the bearing surface. Theother arm |3 of the bell crank lever has a slotted end |5 engaging a pinIS on the end of a rod or link II which extends movably through thevessel wall and, in the case of closed vessels, is suitably sealed tothe wall. For example, the tubular casing B has a horizontal extension|8 which projects through the wall of the vessel I, a gas-tight andliquid-tight seal being made in any suitable manner between said casingsection and the vessel wall.

Vertical movement of the buoyant element thus causes horizontal movementof the rod H the outer end of which operates the pilot valve 6. In casethe vessel 1 is under pressure, said outer end is preferably enclosed ina casing or chamber in which it is subjected to the same pressure as theinner end of the rod within the vessel. In the form shown, the end ofthe casing section 18 is connected and suitably sealed to one leg of aU-shaped block |S, the end of the casing section [6 having threadedengagement at 20 in a bore 2|. Said bore is reduced in diameter at 22and internally threaded to receive a nut 23 having a central openingthrough which the rod [1 passes freely, said nut serving to compresssuitable packing 24 into the end of the bore 22 and around the rod intight engagement therewith. The rod passes out through a small bore 25and across the open space between the legs of the U-shaped block l9,entering the other leg through a small bore 26, packing 21 and a nut 28and terminating in a large bore or chamber 29 which is internallythreaded to receive the nut 28 and also a closing plug 30.

The arrangement described above permits rectilinear reciprocation of therod l1 without gas leaks and substantially without loss of energy exceptfor friction, and leaves a section of the rod between the legs of theU-shaped block exposed for connection to the valve-operating levermechanism to be described so that it is unnecessary to enclose the rodcompletely and also part of said lever mechanism connected thereto. Atthe same time the gas pressures on the opposite ends of the rod arebalanced by providing the block with bored passages 3|, 32 and 33connecting the chamber 29 with the bore 22 and hence with the tubularcasing section [8. The ends of the passages 3|,' 32 and 33 are sealed inany suitable manner as by means of threaded plugs 34.

The exposed section of the rod IT can be connected to the pilot valve 6by any suitable motiontransmitting means. In the form shown, a pin 35 onthe rod engages in the slotted end 38 of a lever 31 which is mounted inany suitable manher, being shown as pivoted at 38 on an arm or bracket39 secured to the block l9. A slot 40 formed in the lever 31intermediate its ends receives the end 4| of a valve operating rod 42which extends into the casing of the pilot valve 6 to operate the valveaccording to the movements of the buoyant element. When the latter is ofthe preferred type having greater effective specific gravity than theliquid, positive action in both directions is assured by suitablycounterbalancing part of the mass of the buoyant element as by means ofa spring or counterweight. For example, the rod 42 is extended so as toproject at 43 from the other side of the pilot valve casing, and theextension 43 is pivotally connected at 44 to the end of one arm 45 of abell crank lever pivoted at 45 on a supporting bracket 41. The other arm48 of the bell crank lever carries a counterweight 49 which isadjustable along the length of the arm 48 and can be secured in thedesired position by a set screw 50. It will be evident that thecounterbalancing system should be adjusted so as to overcome the mass ofthe buoyant element when the liquid is at the level 2, and to beovercome by the mass of the buoyant element when the liquid is at thelevel 3.

As stated above, it is often desirable to render the system insensitiveto variations in liquid level between the upper and lower limits 2 and3. To this end the buoyant element may be suspended in a separatecompartment within the vessel the liquid within said compartment beingmaintained at the upper level 2 by the pressure of the gas above theliquid in the vessel until the level in said vessel falls to the point 3and uncovers a suitable opening through which the liquid in thecompartment can escape. This method of operation also requires theprovision of a one-way gas valve of any suitable type through which thegas in the top of the compartment can, escape as. the, liquid; rises to;the level 2 in both the vessel and the compartment, but: which closes toprevent. passageofv gas in the reversed-irection, into. the. compartmentas! the liquid level falls in the vessel.

In the illustrated embodiment, the tubular casing 8, 18 forms such acompartment, the lower level 3 being determined by the location of thelower end of the casing section 8. At the top of thehorizontal casingsection It is a suitable one- Way or check valve 5| through which gasmay escape from the casing to the vessel, but which closes to preventpassage of gas in the reverse direction. The valve may be spring orweightloaded if desired to delay its opening and hence the: buoyancydifferential effect.

When, desired, the effect of the casing 8 can be eliminated byconnecting the casing. to the vessel so that the gas pressures aremaintained equal. In. the form shown, this can be accom-' pl-ished by aby-pass connection 52 controlledby a. valve 53; also the tubular casingcan be omitted.

The operation of the apparatus will be understood from the foregoingdescription. Insu-mmary, when the, liquid in the vessel is at the level31, the buoyant element is in its lowest position and the pilot valve 6is set to operate the main valve 5 so as to cause liquid to accumulatein the vessel. The liquid thus raises in the vessel until it. reaches adesired level such as that indicated at 21, gas being meanwhileprevented from escaping from the casing to the vessel due to the loadingof the valve 5|. As soon as the valve opens, however, the liquid in thecasing rises rather rapidly to or nearly to the level 2; and thebuoyancy differentialeffect results in the rapid shifting of the leversystem by the counterweight 49 with a kind of snap action so as to shiftthe pilot valve 6 andmain valve 5. The liquid level in the vessel then,falls, but that in the casing section 3' is maintained by the gaspressure in the vessel until the liquid therein reaches the level 3 anduncovers the end of the casing. The liquid in the casing then runsquickly out: until the level, is the same in both the casing. and thevessel, and the increased weight of the buoyant element rapidlyovercomes the counterweight and shifts the pilot valve with, snap actionback. to its first mentioned position.

It will be evident that in the above case the lower level 3 isdetermined. by the location of the lower end of the casing B and the uppr level by the loading of the valve 5!, andv that both can. bepredetermined as may be desired When the valve 5% is: opened, on theother hand, the eiiect of the casing i3 is eliminated and the busy antelement rises and falls with the liquid level in the casing which is thesame as: that. n th vessel. The device is now sensitive to minorvariations in liquid level and can be adjusted so that the level ismaintained practically constant within very narrow limits; forexample,the. discharge of liquid through the valve 5 can be practicallycontinuous and at substantially the same rate as that at which liquid issupplied to the. vessel, the valve 5 operating as a throttling ormodulating valve. The chang from one method of operation to the otherre-l quires only the operation of the valve 53.

Figs. 3-8 show a different type of apparatus for operating the pilotvalve in which the length of the stroke of the valve is increased inrelation to the movement of the rod. I1 and in. which friction effectsare minimized, these results being desirable especially when the valve53 open and; close and exact: instance-Klan er; the limits 2 and 3 is tobe maintained.

The a angement the; rods Hi. 18: nd block s are the same a shown in,Fla. 2. However, compression springs 54. surround: the rod ll on eitherside of. the. pin, 35, each spring being interpqsdibetween, the adjacentlegof the block It and a collar 55 secured tothe rod. The springs arepreferably-installed underlight initial compression and tend to maintainthe rod [-1 in the central positionshown in Fig 3 in which the springsbalance each other. When the rod moves to the left as. shown in. Fig. i:or to the right as Shown in Fig. 5, as the re-.- sult oi a change in,the liquid. l vel, ne or the other spring 54 is compressed, Whentheliquid level changes in the; opposite direction, the force of thecompressed spring supplements that 01 the weight, 1 or of thecounterweight 49 to move the rod quickly back toward its, neutralposition. withoutlag. In this way the friction drag of the bearingsurfaces and especiallyv of the pack in-g 2-4 and 21 on the red, I! isovercome even though very high pressuresact against the pack-. mg.

The lever 56, which correspondsv to the lever 3 of Fig. 2, has a forkedend 51 engaging the pin- 35 and is pivoted on thebracket 3!} at a, point5.8 approximately at the midpoint of thelever. vccordingly the pilotvalve. which isv operated by the other end of the. lever, has a. largermove-H ment for a given displacement of the rod ll than it has in the.arrangement. of Fig. 2. The, upper and lower levelsat. which, the pilotvalve. is actuated can. be adjusted by passing the valve rod. 59through. an; opening 60.. in the end of the lever and providingadjustable stop. 'nuts 61 threaded on the valve rod on. either side ofthe lever. The lever is counterweighted by means of an arm 62. and anadjustable weight 63.

Figs. 6-8. show a form of pi ot valve adapted. for use in agas-bleed-oii yst m. oi control of. the main valve. 5 and especially deigned to minimize frictional effects on the operating system. The valvecasing 6.41 has an inlet 65 fol. gas under pressure and an out et 56'for delivering the gas. to; the main valve 5 for operatin the latter.The casin 64 is tu ular and open at both. ends. and, a cylindricalpiston or plug 5': is movable axially he ca ng y, th valve rod 59,. Anannular groove 613 is formed completely ar und. the inn r rf c i the cing, connecting the inlet. 65 and outlet 56 so that when the piston. Elcovers the groove, gas under pressure is delivered to the valve cas nsect a, but as soon as the piston. is moved to uncover the groove, thepressure in the valve 5, is relieved and the gas escapes through theopen end of the casing 64. The movement of the, Piston needs to be onlyenough tocover and uncover the edge of the. annular groove, and the quidlevel a which these actions occur ar de ned by the ting of. the nuts 6|,

Inasmuch as the, groove 6'8 passes entirely around the plug or piston51,. as. pressures on the latter are balanced at all times, and do notcause binding of the piston in the valve casing. Any tendency of thepiston to bind is further reduced by passing the valve rod looselythrough a slightly larger bore 59 in the piston, the rod carryingadjustabl'e nuts it which are set so that th y do not Quite enga e t ndof the piston. Hence the. valve rod can wobble slightly in the piston,but. the amount of such wobbling is not sufiicient to permit the, valverod 59 to bear against the end of the slot 60 in: the lever 56.

Thus the system illustrated by Figs. 3-8 operates smoothly and incomplete harmony with. the rise and fall of liquid in the vessel i aslong as the valve 53 is open. The levels 2 and 3 are adjustable inaccordance with the setting of the nuts 6!, and can be adjusted andmaintained very close together since the system is practically free oflag. When the valve 53 isclosed, on the other hand, the snap actiondescribed above takes place when the liquid in the vessel reaches thelevel 2 or 3 and the main valve operates as a shut-ofi valve withoutthrottling characteristics, thus reducing the erosive effect of theliquid.

It will be understood that the invention is not restricted to theembodiment described above and illustrated in the drawings, nor to thede-- tails of the foregoing description, since various changes can bemade in the form, details of construction and arrangement of the partswithout departing from the spirit of the invention. Reference shouldtherefore be had to the appended claims for a definition of theinvention.

What is claimed is:

1. Apparatus for controlling the liquid level in a vessel comprisingmeans forming a compartment within said vessel having a liquid outletinto said vessel at the minimum liquid level to be maintained and a gasoutlet into said vessel above the maximum liquid level to be maintained,valve means for said gas outlet subjected to the gas pressure in saidcompartment and moved thereby to open position wh n a predetermined gaspressure is built up in said compartment for the escape of gases fromsaid compartment to said vessel but closing to prevent passage of gasesback into said compartment, a buoyant element in said compartment, meansfor controlling the amount of liquid in said vessel, and meansconnecting said buoyant element with said control means to operate thelatter.

2. Apparatus as defined in claim 1, including a passage connecting saidcompartment with said vessel at a point above the liquid level thereinand a valve for closing said passage.

3. Apparatus as defined in claim 1, said control means being external tosaid vessel. and said. operating connections including a longitudinallymovable rod projecting outside said compartment and vessel, and meansforming a seal around said rod and preventing escape of gas from saidcompartment and vessel.

4. Apparatus for controlling the liquid level. in a vessel comprisingmeans forming a con partment within said vessel having a liquid outletinto said vessel at the minimum liquid level to be maintained and a gasoutlet into said vessel above the maximum liquid level to be maintained,valve means for said gas outlet subjected to the gas pressure in saidcompartment and moved thereby to open position when a predetermined gaspressure is built up in said compartment for the escape of gases fromsaid corn" partment to said vessel but closing to prevent passage ofgases back into said compartment, means outside said vessel forcontrolling the amount of liquid in said vessel, a longitudinallymovable rod projecting through the wall 01 said vessel, means forming aseal around said movable rod, a buoyant element in said compartment,connecting means actuated by vertical movement of said element formoving said rod longitud nally, and connecting means actuated by longi-8 tudinal movement of said rod for moving said control means.

5. Apparatus as defined in claim 4, including a passage connecting saidcompartment with said vessel at a point above the liquid level thereinand a valve for closing said passage.

6. Apparatus as defined in claim 4, including a chamber outside saidvessel into which the end of said rod projects, and means forming a sealbetween the chamber wall and said movable rod, said chamber havingcommunication with said compartment to equalize the pressure on theopposite ends of said rod.

'7. Apparatus as defined in claim 4, said rod extending horizontallythrough the vessel wall, said first-named connecting means includingmeans for translating vertical movement of said element into horizontalmovement of said rod.

8. Apparatus as defined in claim 4, said buoyant element having aneffective specific gravity greater than that of said liquid, andcounterbalancing means tending to move said rod in a direction to liftsaid element, the force exerted on said rod by said counterbalancing J.eans bein less than the force exerted thereon due to the weight of saidelement when said liquid is at said minimum level and being greater thanthat due to the weight of said element when said liquid is at itsmaximum level.

9. Apparatus for controlling the liquid level in a vessel comprising abuoyant element therein, a valve outside said vessel for controlling theamount of liquid therein, a horizontal longitudinally movable rodprojecting outside said vessel, motion-transmitting means connectingsaid element and rod and including means for translating verticalmovement of said element into horizontal movement of said rod, saidelement having an effective specific gravity greater than that of saidliquid, connecting means actuated by longitudinal movement of said rodfor moving said valve, and counterbalancing means outside said vesseland tending to move said rod in a direction to lift said element, thecounterbalancing force exerted on said rod being less than the forceexerted thereon by said element when the liquid is at its minimum leveland greater than the force exerted thereon by said element when theliquid is at its maximum level.

10. Apparatus as defined in claim 9, said counter-balancing meanscomprising a lever mechanism connected to said rod and having asubstantially horizontal arm, and a counterweight adjustablelongitudinally along said arm.

11. Apparatus for controlling the liquid level in a vessel comprising abuoyant element in said vessel, means outside said vessel forcontrolling the amount of liquid therein, a rod movable longitudinallythrough the vessel wall, means forming a seal between said wall and rod,motion-transmitting means actuated by vertical movement of said elementfor moving said rod longitudinally, resilient means tending to move saidrod longitudinally in opposite directions and to restore it to neutralposition when moved away from said position in either direction inresponse to the movement of said buoyant element, and connecting meansactuated by longitudinal movement of said rod for operating saidcontrolling means.

12. Apparatus as defined in claim 11, said controlling means comprisinga pilot valve, said connecting means comprising a lever having one endconnected to said rod, said pilot valve having an operating rod carryingspaced longitudinally adjustable stops and the other end of said leverbeing movable between and into engagement with said stops.

13. Apparatus as defined in claim 12, said pilot valve comprising atubular casing having a circumferential groove, an inlet connection toand an outlet connection from said groove for passage of fluid throughsaid valve to operate said controlling means, and a piston connected tosaid rod and movable axially in said casing in one direction to coversaid groove and in the other direction to uncover said groove andestablish communication between it and the atmosphere.

14. Apparatus as defined in claim 13, said piston having a bore oflarger diameter than said rod, said rod passing freely through said boreand having retaining members at the ends of said piston, whereby saidrod is capable of wobbling in said bore.

15. A pilot valve particularly adapted for the control of a deviceoperated by fluid pressure and comprising a tubular casing having acircumferential groove in its inner surface, an inlet connection to andan outlet connection from said groove for passage of fluid through saidvalve, and a piston movable axially in said casing in one direction tocover said groove and complete the fluid passage between said inlet andoutlet connections, said piston being movable in 10 the oppositedirection to uncover said groove and said casing having an opening tothe atmosphere through which fluid from said groove escapes.

16. A pilot valve as defined in claim 15 including a piston rod, saidpiston having a bore of larger diameter than said rod through which saidrod extends loosely, and stop members on said rod at each end of saidpiston for longitudinal movement of said rod and piston together in bothdirections, the distance between said stop members being greater thanthe length of the piston therebetween so that said rod is capable ofwobbling in said bore.

RALPH WILLIAM HIPPEN. CLAYTON LEE MURPHY, Sr.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 45,437 Richards -1 Dec. 13, 1864 66,018 Gould June 25, 1867542,900 Smith July 16, 1895 1,778,114 Mace Oct. 14, 1930 1,796,537Rossiter Mar. 17, 1931 1,911,785 Bailey May 30, 1933 2,023,560 WagerDec. 10, 1935 2,447,591 Messick Aug. 24, 1948 2,587,401 Spence Feb. 26,1952

